The invention lies in the communications field. More specifically, the invention relates to an authentication process in the context of an inter-system communications handover between two radio communications systems. In particular, the following description deals with the interoperation between UMTS and GSM and to an appropriate handover protocol.
Currently, GSM (Global System for Mobile Communications) is one of the most successful and widely used radio systems for wireless communications. Third generation systems in the UMTS (Universal Mobile Telecommunications System) are being developed. The interoperation and handover scenarios, requirements and priorities must be defined for future use. The inter-operation between UMTS users and networks and GSM users and networks includes the following:
Registration of a user of the one type in a network of the other type, typically including authentication and key agreement. This includes:
a) Registration of a UMTS user in a GSM serving network. [Highest priority.] In countries with existing GSM networks, UMTS networks are expected to be introduced in islands; for nation-wide coverage for GSM-like services the UMTS user will have to rely on the existing GSM network coverage. This is called USIM roaming.
b) Registration of a GSM user in a UMTS serving network. [Low priority.] Whether there is an important need for GSM users to access the UMTS network is under dispute. This scenario might be interesting for GSM operators who want to offer their customers roaming opportunities in those countries that are covered by a UMTS network but not with a GSM network. This is called GSIM roaming.
Inter-system handover of a user from a network of the one type to a network of the other type. This includes:
a) Inter-system handover from a UTRAN to a GSM BSS
a1) Of a UMTS user. [High priority.] In countries with existing GSM networks, UMTS networks are expected to be introduced in islands; for nation-wide coverage for GSM-like services the UMTS user will have to rely on the existing GSM network coverage. Inter-system handover will provide service continuation when the UMTS user leaves an area with UMTS coverage. This is part of USIM inter-system handover.
a2) Of a GSM user. [Lowest priority.] In UMTS-only countries there obviously is no need for inter-system handover from UTRAN to GSM BSS, and vice versa. In countries with both GSM and UMTS networks there is hardly any need for allowing GSM users on the UMTS network, as the GSM coverage is likely to be larger than the UMTS coverage. The only reason to connect a GSM user to a UMTS network might be congestion of the GSM network in some area. This is part of USIM inter-system handover.
b) Inter-system handover from a GSM BSS to a UTRAN
b1) Of a UMTS user. [Medium priority.] In countries with existing GSM networks, UMTS networks are expected to be introduced in islands; for nation-wide coverage for GSM-like services the UMTS user will have to rely on the existing GSM network coverage. This type of handover would allow a UMTS user who initiated a service through a GSM BSS in an area without UMTS coverage, to be handed over to the UTRAN, as soon as possible, and receive the better quality of service. As soon as he is handed over, he may also initiate extra (UMTS) service capabilities. This is part of USIM inter-system handover.
b2) Of a GSM user. [Lowest priority.] The same arguments apply as for inter-system handover in the opposite direction (see 2)a)ii)). This is part of GSIM inter-system handover.
While designing a mechanism to meet these objectives, we assumed that there will be UMTS MSC/VLRs that control both UTRAN and GSM BSS. In addition to that there will be GSM MSC/VLRs controlling GSM BSS.
It is accordingly an object of the invention to provide a method for an authentication for an inter-system handover between at least two radio-communications systems, which satisfies the objects of such systems. The novel process should provide a solution for inter-system handover between GSM BSS and UTRAN controlled by the same UMTS MSC/VLR, but also for inter-system handover to an from a GSM MSC/VLRs controlling GSM BSS.
With the foregoing and other objects in view there is provided, in accordance with the invention, an authentication method for inter-system handover between at least two radio-communication systems, which comprises: performing a system specific authentication by a register of a network depending on a currently supported access method on a radio-interface between a user-equipment and a base station of the radio-communication system.
Other features which are considered as characteristic for the invention are set forth in the appended claims.
Although the invention is illustrated and described herein as embodied in a method for an authentication for an inter-system handover between at least two radio-communications systems, it is nevertheless not intended to be limited to the details shown, since various modifications and structural changes may be made therein without departing from the spirit of the invention and within the scope and range of equivalents of the claims.